Armor Attack Vectorbeam Monitor Smoke

Well I just finished replacing nearly every component on the Cinematronics monitor. About 60$ in parts and 20 in shipping from both Digikey and Newark. I followed Bill's excellent guide for this project. http://www.biltronix.com/arcade_electcomp_01.html#star_castle Powered it up last evening and it cooked R213. So now I'm wondering just why a 200ohm 1/4 watt resistor would go like that. Not sure if it was just the heat but R217, a 100Ohm 1/4w resistor isn't looking any better for the wear as it has a black band now in the middle.
I'm confident I installed everything accurately. Going to double check the work again tonight. Hopefully radio shack has some 200 ohm 1/4w resistors. But I've never known a resistor to go just because it's old.
I double checked that transistors weren't installed backwards. Looked for shorts anywhere.
Anyone have any idea why R213 would cook after installing all brand new parts?
I think the only parts I did not replace were the 2 Dac 80's at 13$ a pop.
 
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Both R213 and R217 are on the Horizontal circuit. R213 connects to the emitter of Q202 if 213 burned, you probably should check Q202 for also being shorted and possibly Q201 and Q203.

Did you replace the two diodes at D205 and D206?

I don't think a bad DAC would cause this sort of issue, you can swap them around and test.
 
Yea I had replaced both D205 and D206 as well as Q202, Q201 and Q203. I will double check everything tonight. I already double checked the diodes to ensure I got them all running in the proper direction.

Both R213 and R217 are on the Horizontal circuit. R213 connects to the emitter of Q202 if 213 burned, you probably should check Q202 for also being shorted and possibly Q201 and Q203.

Did you replace the two diodes at D205 and D206?

I don't think a bad DAC would cause this sort of issue, you can swap them around and test.
 
Ok, I replaced D205 and D206 with the old diodes that were in there before. While I was at it, I also replaced Q201, Q202 and Q203 with a new order of them from elsewhere for good measure.
I am now getting this and the R213 is holding solid. I am now wondering if this is a POT problem as I'm not getting any reaction from adjusting the replaced pots. May just throw the old ones back in.
 

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If you swap the two DACs around, does it change at all?

From the pictures, I would guess either the LF1331 analog switch or the 7400 series chip that is on the monitor board. It is something like a 7404 or 7406 (going from memory here).

Have you tested your board in another game?
 
Ack! I got it. I decided to replace the brand new diodes with the original and also replaced the Q101, Q102, Q103 transistors with other sourced. Basically the same I did with other side of deflection.
While working on this I also took a closer look at the pots. I found a missing pad on R201 leading to another circuit. I took an exacto knife to get to the trace and created a solder bridge to the pot.
Nailed it! Thanks man.
Next time I'll get my big head out of frame.
 

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